When nerves are severed or damaged otherwise, stimulations inside and outside the organism may not be properly transmitted. This may be very hazardous to the organism. Especially, spinal nerves are known as one of the most difficult-to-regenerate human tissues. Once the spinal nerves are damaged, the function of the motor and sensory nerves may be permanently lost. Damage to the spinal nerve causes severe pain in addition to the loss of motor function, as well as many complications such as cystitis, bedsore, autonomic hyperreflexia, muscle spasm, heterotopic ossification, etc., leaving patients in pain in their lifetime.
For functional recovery of the damaged nerve, various therapies including cell therapy, tissue engineering-based therapy, rehabilitation therapy, drug therapy, nerve stimulation-based therapy, etc. are studied, but they have the following limitations.
Cell therapy involves introduction of bone marrow-derived stem cells to the damaged nerve to induce regeneration of the nerve tissue. However, it is still difficult to remain the cavity in the spinal cord, and the introduced stem cells exhibit low viability.
Tissue engineering-based therapy employs a tissue engineering support or stem cells to induce regeneration of the nerve tissue. However, this method is effective only for the peripheral nerves which have excellent regenerating ability, and its application is restricted.
As for drug and rehabilitation therapies, there is no drug available for the functional recovery of the spinal nerve, and the rehabilitation therapy is only a supplementary measure to improve conditions.
Treatment using an apparatus for stimulating nerves is based on electrical stimulation using implantable electrical/electronic devices and software for controlling them, without drug administration. However, the existing nerve-stimulating apparatus allows only the recovery of cerebral function as well as the relieving of pain.
Accordingly, they are restricted in recovering the function of damaged nerves by regenerating them.